Industrial robot wrist unit

Abstract

A wrist unit for an industrial robot comprises a wrist housing detachably mounted to a distal end of a robot arm, the wrist housing containing rotatably mounted first and second, parallel, secondary drive shafts on the input ends of which are mounted cylindrical driven gears for engagement with the respective cylindrical drive gears located on primary drive shafts on the robot arm. The driven gears and the drive gears are so disposed that an imaginary line extending through the centers of the gears are offset from the center axis of the coaxial drive gears, the wrist housing being radially adjustable on the end of the robot arm for adjusting the gear clearance between the drive gears and the driven gears.

What is claimed is: 
     
       1. A wrist unit for an industrial robot, comprising a wrist housing detachably mounted to a distal end of a robot arm, the wrist housing including a pivotally mounted tilt housing which supports a rotatably mounted turntable for supporting an external tool, first and second secondary drive shafts rotatably mounted in the wrist housing, said first and second secondary drive shaft each having an input end supporting driven gears for engagement with drive gears respectively located on primary drive shafts in the robot arm, said drive gears being coaxial and axially spaced, the turntable being rotatable about a first axis by the first secondary drive shaft via a respective first gearing, the tilt housing being pivotable about a second axis by the second secondary drive shaft via a respective second gearing, and the first and second axes intersecting, the improvement wherein the driven gears and the drive gears are disposed relative to each other so that an imaginary line, extending through centers of the driven gears, is offset from a centerline of the drive gears, and wherein the wrist housing is radially adjustable on the end of the robot arm for adjusting the gear clearance between the drive gears and the driven gears. 
     
     
       2. The wrist unit according to claim 1 wherein the driven gears and the drive gears are each cylindrical. 
     
     
       3. The wrist unit according to claim 1 wherein the wrist housing is of a single piece construction.